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2 Sheets-Sheet1. T. A. EDISON. Speaking-Telegraph. No. 203,014. PatentedApril 30, 1878.

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2 Sheets-Sheet 2.

T. A. EDISON. Speaking-Telegraph. No. 203,014. Patented April 30,1878.

/waufai w Imam I 8 UNITED STATES THOMAS A. EP'QON, OF MENLO PARK,

PATENT ()FFICE.

NEW JERSEY, iissienon TO wnsrnnx UNION TELEGRAPH COMPANY, OF NEIV YORK,N. Y.

IMPROVEMENT IN SPEAKlNG-T'ELEGRAPHS.

Specification forming part of Letters Patent No. 203,014, dated April30, 1578; application filed July 20, 1877.

'10 all whom it may concern:

Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county ofMiddlcsex and State of New Jersey, have inventedau 1m.- provement inSpeaking-'Telegraphs, of which .the following is a specification:

I make use of :a resonant case with several tympans, adjusted todifl'crent degrees of tension or delicacy, and theseare all so connectedwith contact-points in the metallic line-circuit that the electricpulsations will be sent over the line from one or more of these tympans,and operate upon an electro-magnet and receiving-tympan of a resonator.By this arrangement it is sought to produce such undulationsof theelectric currents passing over the line that they will represent theinflections of the human voice speaking into the transmit-.ting-resonator, and therefore the receiving-imstrument will becorrespondingly influenced.

In the drawings, Figure 1 is a plan view,partially in section; and Fig.2 is an end view .of

one tympan and circuit-closing device.

Thebox a is of a suitable size and shape.

At one side thereof there is a mouth-piece, b,

adapted to receiving the sounds of the human voice as spoken into theresonant box a. Thismouth-piece may be upon the topof the box, or at oneof the sides thereof. It is preferable that the hollow resonant box becubical, in order that at its sides may be placed the tympans aforesaid.I have shown four such tympans.- Each tympan is .madesimilar to thehead'of akettle-drum, but preferably of a plate of metal, and it coversan opening in one of the sides of the resonant box. The edge of thetympan e is etween the rings k, and rests against the end of thecylinder h,- and there are screws f,by. which to adjust the rings andapply greater or less strain to the tympan. The tympans are allconnected with the metallic line-circuit L, and in front of each thereare one or more circuit-closing springs, i, preferably with carbon orplumbago points, and each spring is adjusted by the screw o, s o thatthe point is in nearer or more remote proximity to the tympan. Thesprings t are all in theci'rcuitt to the battery M B, and there is aground-connection at G, and a shunt from the main line 'L to G, in whichis placed a rheostat, R, and magnet-helix M,to neutralize the staticcharge and discharge. t

It will now be evident that whenever the tympans, or any one ofthe1n,are vibrated by the action of the voice,the linecircuit will beconnected to the-battery, and pulsations sent that represent thevibrations of the tympan. I therefore construct or adjust the tympans sothat'they respond to different tones or modulations of the voice, inorder that when a person speaks into the resonant box the sound willberesponded to by one or more of the tympans,

and pulsations will be sent upon the line (so efficiently, so that thevarious modulations and tones of the voice will be represented by theelectric pulsations,which, acting upon an elec- I troqnagnet at thereceiving-station, will influence the resonant receiver and produce thesame tones, whereby the articulation will be apparent to a listener.

011 very long lines, owing to the excessive weakness of sound inuttering the hissing consonants, the electric pulsations resultingtherefrom at a certain distance cease to be perceptible. To overcomethis, I arrange thedevice shown in Figs. 2 and 3 in place of one of thetympans, so as to increase the strength of the consonant waves, as inch, S, '1, I. This is accomplished by using a plate, 0, with a smallhole or slot near the center, in front of which is stretched a strip orpiece ofshcct-rubberm,that

is secured near each edge of the disk 0, and laps a little over the holein c; and upon the rubber is secured a small piece oi'platina-foil, u,an arm of which runs over to and makes connection with the plate 0.immediately opposite is a platina contactscrcw, in, which is connectedto the battery through a resistance, R; and by regulating this, thehissing parts ofspeech may be increased or decreased instead of beinglost, as in the other tympans, owing to the minute amplitude given themby these sounds, and also to. the enormous resistance of the plumbagopoints to the slight pressure which these vibrations give. By using aplatina point these vibrations are rendered very loud, and by theemployment of the rubber in front oil .the aperture in a great amplitudeis obtained,

evento the iaintest hiss. V V I do not herein make any claim to thetransmiion ol'electriccurrents varying in intensi- 1 2. The plate 0,provided with an aperture, 1 proportionately to the stmml-vihrations, asI an elasticmembrane,and circuit-breaking conthat i.\ set forth inapplications heretofore tiled nections, arranged and operatedsubstantially by me; and in my application No. 141, plum- I for and inthe manner set; forth.

hago is described as acted upon by the \'ihra- Signed by me this 16thday of July, A. I). tions of the diaphragm. I (to not, therefore, T877.

elaim the same herein.

1 claim asanyinventi0n THOS. ED SON. 1. The eomhination, in thetelegraphic eir- ('llilS 0f two m' more tympans, a resonant box,\\'itnesses:

and one or more circuit-(losers to eaeh t \'m- (H10. '1. PINFKNI'IY,pan. substantially as set forth. I HAROLD SI'IRRHLL.

